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Causes AuthService to check
IsVariablePolicyEnabled() before enforcing
write protections to allow variable deletion
when policy engine is disabled.

Only allows deletion, not modification.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Cc: Bret Barkelew <brbarkel@microsoft.com>
Signed-off-by: Bret Barkelew <brbarkel@microsoft.com>
---
 SecurityPkg/Library/AuthVariableLib/AuthService.c       | 22 ++++++++++++++++----
 SecurityPkg/Library/AuthVariableLib/AuthVariableLib.inf |  2 ++
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/SecurityPkg/Library/AuthVariableLib/AuthService.c b/SecurityPkg/Library/AuthVariableLib/AuthService.c
index 2f60331f2c04..aca9a5620c28 100644
--- a/SecurityPkg/Library/AuthVariableLib/AuthService.c
+++ b/SecurityPkg/Library/AuthVariableLib/AuthService.c
@@ -19,12 +19,16 @@
   to verify the signature.

 

 Copyright (c) 2009 - 2019, Intel Corporation. All rights reserved.<BR>

+Copyright (c) Microsoft Corporation.

 SPDX-License-Identifier: BSD-2-Clause-Patent

 

 **/

 

 #include "AuthServiceInternal.h"

 

+#include <Protocol/VariablePolicy.h>

+#include <Library/VariablePolicyLib.h>

+

 //

 // Public Exponent of RSA Key.

 //

@@ -217,9 +221,12 @@ NeedPhysicallyPresent(
   IN     EFI_GUID       *VendorGuid

   )

 {

-  if ((CompareGuid (VendorGuid, &gEfiSecureBootEnableDisableGuid) && (StrCmp (VariableName, EFI_SECURE_BOOT_ENABLE_NAME) == 0))

-    || (CompareGuid (VendorGuid, &gEfiCustomModeEnableGuid) && (StrCmp (VariableName, EFI_CUSTOM_MODE_NAME) == 0))) {

-    return TRUE;

+  // If the VariablePolicy engine is disabled, allow deletion of any authenticated variables.

+  if (IsVariablePolicyEnabled()) {

+    if ((CompareGuid (VendorGuid, &gEfiSecureBootEnableDisableGuid) && (StrCmp (VariableName, EFI_SECURE_BOOT_ENABLE_NAME) == 0))

+      || (CompareGuid (VendorGuid, &gEfiCustomModeEnableGuid) && (StrCmp (VariableName, EFI_CUSTOM_MODE_NAME) == 0))) {

+      return TRUE;

+    }

   }

 

   return FALSE;

@@ -842,7 +849,8 @@ ProcessVariable (
              &OrgVariableInfo

              );

 

-  if ((!EFI_ERROR (Status)) && IsDeleteAuthVariable (OrgVariableInfo.Attributes, Data, DataSize, Attributes) && UserPhysicalPresent()) {

+  // If the VariablePolicy engine is disabled, allow deletion of any authenticated variables.

+  if ((!EFI_ERROR (Status)) && IsDeleteAuthVariable (OrgVariableInfo.Attributes, Data, DataSize, Attributes) && (UserPhysicalPresent() || !IsVariablePolicyEnabled())) {

     //

     // Allow the delete operation of common authenticated variable(AT or AW) at user physical presence.

     //

@@ -1960,6 +1968,12 @@ VerifyTimeBasedPayload (
 

   CopyMem (Buffer, PayloadPtr, PayloadSize);

 

+  // If the VariablePolicy engine is disabled, allow deletion of any authenticated variables.

+  if (PayloadSize == 0 && (Attributes & EFI_VARIABLE_APPEND_WRITE) == 0 && !IsVariablePolicyEnabled()) {

+    VerifyStatus = TRUE;

+    goto Exit;

+  }

+

   if (AuthVarType == AuthVarTypePk) {

     //

     // Verify that the signature has been made with the current Platform Key (no chaining for PK).

diff --git a/SecurityPkg/Library/AuthVariableLib/AuthVariableLib.inf b/SecurityPkg/Library/AuthVariableLib/AuthVariableLib.inf
index 8d4ce14df494..8eadeebcebd7 100644
--- a/SecurityPkg/Library/AuthVariableLib/AuthVariableLib.inf
+++ b/SecurityPkg/Library/AuthVariableLib/AuthVariableLib.inf
@@ -3,6 +3,7 @@
 #

 #  Copyright (c) 2015 - 2016, Intel Corporation. All rights reserved.<BR>

 #  Copyright (c) 2018, ARM Limited. All rights reserved.<BR>

+#  Copyright (c) Microsoft Corporation.

 #

 #  SPDX-License-Identifier: BSD-2-Clause-Patent

 #

@@ -41,6 +42,7 @@ [LibraryClasses]
   MemoryAllocationLib

   BaseCryptLib

   PlatformSecureLib

+  VariablePolicyLib

 

 [Guids]

   ## CONSUMES            ## Variable:L"SetupMode"

--
2.26.2.windows.1.8.g01c50adf56.20200515075929


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